The gordius is likely a fine option, I just don't know enough about it to comment. However, I'll tell how I would do this.
You could program this thing to send a midi note on when it receives a certain note off. Kinda of pricey and complicated to program, but it works.
Second option (my current favourite) is to use a raspberry pi with the Satellite CCRMA disk image loaded. This comes with pure data installed and you can use a midi-to-usb cable to insert the raspberry pi between your FCB and your LP1 to introduce all sorts of scripting options: Note off to note on, note sequences, different scripts based on how long you hold a note down... if you're handy with pure data, it's a fairly cheap option and it works really well.
Sylvain
